This invention relates to a manufacturing process. The invention also relates to an associated apparatus. The process and apparatus may be used exemplarily in the manufacture of elongate, axially symmetric products. In the food industry, the method and apparatus are useful in the manufacture of meat products such as frankfurters, hot dogs, sausages or wursts or in the production of baked goods such as cakes and breadsticks. The process and method may also be used for forming elongate structural members such as solid or hollow rods or beams.
Frankfurters, hot dogs and other sausages are conventionally made by first comminuting meat along with spices, emulsifiers, flavors, preservatives and other additives to form an emulsion which may be a smooth flowable paste or may contain chunks of meat, cheese, vegetable matter or other ingredients. This emulsion is then stuffed into casings which may be edible or inedible. The encased emulsion is conveyed through a cooking system which ordinarily slowly raises the temperature of the emulsion, often in several steps, in order to cook the emulsion. The heating is usually done by hot air, both dry and moist, to a final temperature of approximately 162.degree. F.
Most households in the U.S. today prefer frankfurters to be skinless, that is, without a casing which must be removed before frankfurter consumption. In the preparation of skinless sausages, the processor must remove the skin before final packaging in vacuum-sealed plastic bags. This process involves the physical stripping of the casing by hand or machine and discarding the used plastic wrap.
A significant problem with the conventional procedure is the cost and handling of the inedible casings. A manufacturer may pay several millions of dollars per stuffer line for the casings and then pay to dispose of them. This adds a significant cost to the manufacturing process. One facility has estimated a $5 million dollar per year revenue increase if this cost could be eliminated. And this estimate does not take the front office, purchasing and machinery capital costs into account.
Simply eliminating the casing step is not considered possible because the hot dog must be formed and held together before and during the cooking step. Otherwise, the emulsion will not hold its shape and the product will be ruined. Whatever method is devised must lend itself to high speed production techniques and not alter the taste and look of the product as well.
Although the concept of creating frankfurters or wursts without a casing has been well documented in prior art patents, most of these techniques have centered upon using standard heating platens or molds to create a skin on the product before final processing. These techniques have not been met with widespread acceptance since conductive or convective heat energy is expensive. When a platen is heated, much heat is lost to the surrounding environment or through conduction to the rest of the metallic apparatus. In addition, creating a skin by such methods is time consuming, thereby reducing the production throughput or requiring significant investment in capital equipment to keep output rates high.